Turning air humidity into electricity
One of the latest trends in ambient energy harvesting research is the development of moisture electric generators (MEGs). These experimental devices convert naturally occurring water vapor in the air into electrica energy.
The technology was not designed to support national power systems. Instead, it targets the growing demand for energy sources capable of powering wearable electronics, distributed sensors and temporary devices such as biodegradable medical technologies.
As these applications expand, researchers are increasingly searching for alternatives to conventional batteries. Beyond practical considerations, battery disposal and recycling remain major sustainability challenges, especially for single-use electronics such as smart patches and disposable sensors. In some cases, recovering spent batteries is simply not feasible.
How moisture electric generators work
MEGs, short for moisture-enabled electric generators, are attracting growing attention because they rely on simple operating principles and widely available, non-toxic materials.
The devices absorb water molecules from the surrounding air through their hydrophilic regions. In wearable applications, moisture can also come directly from human skin.
As water is absorbed, ions and protons are released and begin to move. Because moisture distribution and evaporation occur unevenly throughout the device, concentration gradients form, driving the charged particles in a single direction.
When connected to an external circuit, this movement generates a continuous electric current. In many designs, chemical reactions at the electrodes help stabilize and extend power generation over time.
A moisture electric generator made from food-grade materials
Researchers from the Queen Mary University of London, the University of Warwick, the Imperial College London and the Universitas Mercatorum have redesigned the traditional moisture electric generator to improve its environmental performance.
Instead of conventional synthetic polymers, the team used food-grade materials including gelatin, table salt and activated carbon to create a stable yet biodegradable MEG.
The device was produced using a drying-induced self-stratification process. All materials were deposited together in a water-based mixture. As the film dried, the components naturally separated into two distinct layers.
One layer, composed of gelatin and salts, is responsible for absorbing moisture from the air. The second layer, rich in activated carbon, provides directional charge transport.
This asymmetric structure creates an internal pathway that promotes continuous cycles of water absorption and evaporation, maintaining a steady flow of electrical charges.
Performance and scalability
The bio-based moisture electric generator produced a stable and continuous electrical output of approximately 1 volt for periods exceeding 30 days.
By connecting multiple units in series, the researchers achieved scalable performance reaching up to 90 volts and 5.08 milliamps, enough to power small electronic devices such as a string of 40 LEDs.
These results highlight the potential of moisture electric generators for low-power applications, including wearable technologies, environmental monitoring systems and future distributed sensing networks, sectors that are also expanding across Africa and other emerging markets.
Designed for sustainability and end-of-life recovery
The environmental benefits extend beyond operation.
Tests showed that the moisture electric generator biodegraded in soil within a few weeks. The device can also be recycled through a water-based process involving dissolution and remolding.
“Our goal was to rethink how electronic materials are designed and manufactured,” the researchers explained. “This research demonstrates that it is possible to create high-performance energy devices using low-cost and environmentally friendly materials.”
The study, titled “A biobased moisture-electric generator with self-stratified architecture for physiological sensing and energy harvesting,” was published in Nano Energy (2026). DOI: 10.1016/j.nanoen.2026.112040.